Drilling fluids



United tes Patefit 2,956,948 Patented Oct. 18, 1960 DRILLING FLUIDS Russell L. Sperry, Ojai, Calif. Keystone Labs Inc., 340 E. Santa Clara St., Ventiira, Calif.)

N Drawing. Filed Aug. 4, 1958, Ser. No. 753,077

8 Claims. ct. 2s2 s.s

This invention relates to the productionof synthetic chemical compounds from organic materials and their use in drilling muds for deep wells to reduce water loss in drilling. This application is a continuation-impart of my earlier application Serial No. 558,620, filed January 12, 1956, now US. Patent No. 2,881,211 and entitled Synthetic Resinous Materials, Their Production by Acid Charring of Carbohydrates, Acid Derivatives Thereof, Alkali Metal Salts of Such Acids, and Drilling Muds Containing Acid Derivatives and Alkali Metal Salts Thereof.

One object of the invention is to produce novel, synthetic, organic compounds from naturally occurring organic materials known generally as carbohydrates, including the saccharides, and also sometimes collectively called saccharides.

Another object of the invention is to provide new and effective reagents for conditioning well-drilling muds, more Specifically clay-Water base drilling fluids.

It is a still further object of the invention to produce high-molecular weight polycarboxylic acid compounds from carbohydrate materials, and the like, particularly those having five or more carbon atoms per unit sugar molecule i. e. per sugar unit in each molecule) and to use acids produced therefrom, and alkali salts of such acids, in oil-well drilling muds for reducing Water loss during drilling, for reducing the viscosity of the muds, and for emulsifying oil therein.

A further object of the invention is to convert carbohydrates, such as glucose, sucrose, starch, hemi'cellulose, cellulose, and like carbohydrate derivatives which are hydrolyzable to pentoses, or hexose-s, to highmolecular; weight carboxylic acid materials, or their alkali metal salts.

It is also an object of the invention to produce, by acid dehydration or char-ring of the indicated raw materials, black resin-like materials of relatively inert nature and high carbon content (approximately 65 %to 71%), it being also an object to conv'ei'rt such resin-like products by fusion or digestion with st r'ong alkali-s (particularly the Group I alkali metal hydroxides), at high temperatures to form the water-soluble alkali riietal salts of corresponding acidic derivatives of the =resin like materials, it being also an object of theinventibn to, prepare free acids from the indicated salts, as byacidi zing solutions of the indicated alkali metal salts, accompanied with the recovery of the acids, which are precipitated.

A still further object is to employ 'suchacidic materials, either in the salt form or in a recovered acid form, to condition drilling muds, for such purpos ing the water-loss and viscosity of the mud, improve the wall-cake characteristics, ahd emulsifying oil thernud.

By the term carbohydrate in this application, I r e to that general class of natural organic compdiiiids' includes simple sugars, such as the pentose's and hexoses, the disaccharides such as sucrose, lactose, mannose, and the polysaccharides, such as cellulose,- staich, dext'r'iii and dextran, and also derivatives of the carbohy- 2' drate's, such as pectins and pectic acids, the gums, such as gum arabic, and other similar materials which are hydrolyzable to pentose or hexose sugars, or hexuronic acids or similar carbohydrates.

The term saccharides broadly may also be used as synonymous with the term carbohydrates, and by this term I mean to include monosaccharides, the di-, tri-, and tetrasaccharides, including the group called c-ligosaccharides, and all other polysaccharides containing several or many sugar units. In fact, herein the term polysaccharides may be taken to include all saccharides above the monosaccharides.

I have discovered that the carbohydrates and derivatives thereof may be charred with strong mineral acids, more particularly sulfuric acids (including sulfur trioxide) and hydrochloric acid, preferably sulfuric acid, under controlled conditions, to yield a black, resin-like, almost inert material which, however, is largely made up of a product soluble in alkali metal hydroxide solutions at high temperature only, that is, in the. neighborhood of 450 F. or above, e.g. up to 550 F..0r 600 F. Whereas, the complete acid-catalyzed destructive distillation of wood (cellulose, et cetera) to carbon and a variety of organic acids and phenols is well known, this invention relates to the almost quantitative conversion of carbohydrates, including celluloses, to an intermediate black resin-like product which in turn can be. converted almost quantitatively tothe alkali-metal salts of highmolecular-Weight polycarboxylic acids by fusion with, or digestion in Water with, alkali-metal hydroxides at temperatures of around 450 F. and above. Although concentrated acids, such as fuming or 98% H are good for chairing, concentrations down to 60%, 50%, 20% and even lower such as 5% in the case of H 904, are usable, it being, however, necessary that there-be sufficie'nt acid on a Water-free basis to char the quantity of carbohydrate being treated. While chairing with dilute sulfuric acid may require a few hours, e.g., two to five hours at around F. to F. or within a range between about 150 F. and 250 F. to 300 F., digestion with moderately strong alkali metal hydroxides may require only a few minutes. For' example, digestion with sodium hydroxide solution of at least 30% concentration, or in the order of 60% concentration, may complete the solution of the materials soluble therein at 500 F. to 550 F. within a period of about five' minutes. While sodium hydroxide (or potassium hydroxide or lithium hydroxide) concentration may be maten'ally lower than 30%, thus requiring longer digestion periods (perhaps one-half hour to one hour), there is no advantage when working with such lower concentrations, especially since it is very desirable to employ a caustic solution of relatively high concentration in the indicated high temperature range for only a few minutes. The free acids are precipitated by acidifying a solution of the alkali metal salt and may be recovered in the usual manner.

The yields, analyses, and properties of the chars, and of the free acids derived by the above process from glucose, sucrose, starch, pure alpha (a) cellulose, and cotton are so closely identical as to indicate a constant composition. Infra-red and element analyses of the freeacids derived from alpha cellulose by this pr o'ess proved the product to be a high molecular weight polycarboxylic acid containing hydroxyl groups of approximate formula (C H O Every analysis of the acids derived tram these various carbohydrates 'fell Within the range indicated by the following formu15ftc r1' ,o 7

There is a very great variety of source materials falling within the class of carbohydrates having five or more carbon atoms per molecule of each basic sugar unit, and, so far as is presently known, all such materials of this general classification of carbohydrates or saccharides are usable. Thus the following pure materials have been successfully converted through the intermediate resin to the free acids: glucose, arabinose, sucrose, alpha cellulose, starch, dextran, xylose, pectin, algin, and carboxy methyl cellulose. Also the following crude carbohydrate products have been converted to the acids, the properties varying from those above only to the extent that should be expected as a result of the impurities present in the raw material: wood, sawdust, wood bark, wood pulp, wood excelsior, kraft paper, corn cobs, corn stalk, beet cossettes, Quaker Oats Companys Furafils, seaweed algins, etcetera. The almost unlimited sources of raw materials available include cotton gin waste, oat hulls, waste paper, sugar cane bagasse, cotton seed hulls, lignocelluloses, starches, beet cossettes, etcetera.

Other materials include straw, nut shells, rice, wheat, potatoes, hemp, jute paper and paper pulps, pectic acids, gum arabic, the hexoses and pentoses, celluloses, pentosans, and similar materials hydrolyzable to pentose and hexose and hexuronic acids. The mentioned Furafils are the residue remaining from the commercial preparation of furfural from waste corn products (cobs, etc.), which residue contains about 45% cellulose plus other carbohydrate and organic materials.

As a consequence of the above listings of usable carbohydrates (or saccharides) it is apparent that the classification of raw materials to be used as stocks includes all the carbohydrates containing 5 or more carbons per sugar unit in the molecule and all the monosaccharides, and di-, tri-, and higher polysaccharides, such as starches, and the refined and crude celluloses and cellulosic vegetable waste.

PROCEDURE The procedure as a whole involved in this improvement involves several steps which principally include the following:

Step I.The carbohydrate material is charred with acid preferably sulfuric acid or acceptable strong hydrochloric acid, under appropriate conditions.

Step Il.The char may be crushed and washed with water to remove residual acid.

Step III.--The char, wet or dry, is mixed with alkali metal hydroxide such as sodium hydroxide, both the char and the hydroxide being preferably powdered or crushed, or such powdered or crushed char is slurried in a water solution of the alkali metal hydroxide. By fusion of the char and hydroxide mixture (starting wet or dry) at a temperature of about 450 F. or above, such as up to 600 F., or by digestion of a water slurry of the mixture in a pressure reactor at about 450 F. or above, the char is converted to water-soluble salts of high-molecularweight organic acids. Such salts may be recovered from the aqueous solution as by evaporating to obtain substantially pure salts containing perhaps residual alkali metal hydroxide, and carbonates.

Step IV.-Water solution of the sodium salts formed as above is acidified with mineral acid such as sulfuric acid, or with weak organic acid such as acetic acid, whereupon the high-molecular-weight synthetic acids produced by the charring and the high temperature reaction with the alkali metal hydroxide are precipitated at about 7 pH or lower pH. The precipitated high-molecularweight acids are then isolated and washed with water to remove soluble materials.

The char produced by Step I above is a black resinl ike material which may sometimes hereafter be referred to as a resin. The reaction of this char or resin with alkali metal hydroxide as in Step I converts the char largely to the indicated high-molecular-weight acid salts, which is the only characterizing reaction of the desired product of Step I which is, at the present time, known to me.

When properly prepared from pure saccharides 0.

carbohydrates, the washed and dried char requires a minimum of about 40% by weight of sodium hydroxide (or the equivalent potassium hydroxide or lithium hydroxide) based on the weight of the char to effect complete conversion to the corresponding high-molecularweight acid salts. The pH of such alkali metal salts is about 9.0 to 10.5 in water solution. The highest overall conversion of carbohydrates to the water-insoluble acid-insoluble high-molecular-weight organic acids of Step IV has been 58% based on dry glucose, sucrose, alpha cellulose, and starch, these being 60% to 68% yields of resin," with to 94% conversion of the char or resin to such high-molecular-weight organic acids. The char when properly prepared from pure carbohydrates as above indicated is insoluble in all of the common solvents which have been tested, such as: benzene, xylene, acetone, alcohols, dioxane, ethylene glycol, water, benzine, and triethanolamine, and is insoluble in caustic solution of 5% to 50%, even at 350 F. but reacts and becomes completely soluble in caustic solution of 5% to 50% at about 450 F. or above, as previously indicated. Even at 450 F., the reaction is relatively slow and often requires an hour or more to go to completion. At 490 F. to 500 F. or above, such as up to 600 F., the reaction appears almost instantaneous, since completed conversion has often been obtained in five minutes at 500 F.

When mixed materials, such as wood products and byproducts, oat hulls, corn cobs, Quaker Oats Companys Furafils and the like are used in this process, the char obviously may contain many non-carbohydrate materials which were originally present and were and may remain soluble in water, caustic solution, or other solvents, so that such partial solubility of chars prepared from such raw materials cannot be interpreted to mean that the carbohydrates present were not converted in large measure to the char or resin described herein.

Specific procedures under the various Steps I, II, III, and IV, as above indicated, are given below, with an appreciable number of examples which detail and clarify the various sequences, much of this material being presented in outline form in order to be more readily understood.

Step 1Preparation of resin-char A. USING CONCENTRATED ACIDS Most carbohydrates dissolve readily in about 80%, or stronger, sulfuric acid, with evolution of heat. If such a solution is heated to about F. to F. or the temperature rises as a result of the exothermic dissolution, a vigorous exotherm results with the formation of the desired resin char.

Example 1.-17.5 gm. paper hand toweling was dissolved in 40 gm. concentrated (98%) sulfuric acid. Shortly after solution was complete, the temperature of the reaction mass rose from about 140 F. to 280 F. within a few minutes, some S0 and S0 was evolved, and the slurry increased in volume and set-up to a semisolid black mass. The mass was crushed, washed thoroughly with water, and dried to yield 10.0 gm. of resin-char for a 64% recovery, based on the dry weight of the paper (15.6 gm.).

Example 2.-17.5 gm. kraft paper was dissolved in 90 gm. of cold 98% sulfuric acid. During the following half hour the solution expanded, set up to a black jelly, and finally set up to a semisolid. The washed and dried product weighed 9.5 gm. for a 61% recovery based on the dry weight of the paper (15.6 gm.).

The resin-chars above were insoluble in boiling 50% sodium hydroxide solution, but by the general procedures as described above a 35% conversion to high-molecularweight acids was effected by heating 4.5 gm. char, 4.5 gm. NaOH and 15 gm. water in a pressure reactor at about 465 F. for 1 hour; also a 70% conversion was reflected by fusing 3 gm. of char and 3 gm. NaOH from 480 F. to 550 F. for a few minutes. were recovered as indicated above.

Example 3.- gm. of dry, powdered sugarlsucrose) was added with mixing to 10 gm. concentrated sulfuric acid. The exothermic conversion to a solid black mass was complete within five minutes of completing the addition. 6.8 gm. or 68% yield of resin char was recovered.

Example 4.-10 gm. of dextrose was dissolved in 20 gm. 98% sulfuric acid, and heating for minutes at 100 C. (212 F.) converted the solution to a solid black char. The result was a 52% yield of resin, insoluble in boiling caustic, but fusible with caustic at high temperature (as herein described) to yield soluble-salts.

Example 5.An identical reaction to that of Example 4 using concentrated (37%) HCl instead of sulfuric acid yielded 40% of insoluble resin or resin char.

Example 6.10 gm. Marasperce C, a commercial lignocellulose, was slurried in 36 gm. 98% sulfuric acid, and 6 gm. or 60% yield of black resin was formed during the vigorous exothermic reaction. This product was identical to the above chars with regard to reaction with sodium hydroxide.

Example 7.100 gm. of Quaker Oats Companys Furafil C was mixed with 50 gm. of 80% sulfuric acid to obtain uniform wetting. The mix was heated over night at 180 F. to 190 F. The thoroughly washed, and dried char weighed 65.5 gm. for a 65.5% yield.

This char was converted to soluble sodium salts by heating 14.7 gm. thereof and 5.7 gm. NaOH in 200 cc. of water at 480 F. to 500 F. for /2 hour.

Concentrated sulfuric acid for the above examples may vary between 80% and 100% H 50 Fuming sulfuric acid containing free S0 may be used although no apparent advantage results.

The free acids B. USING DILU'IE SULFURIC ACID Example 8.15.6 gm. of kraft paper was soaked in 90 cc. of sulfuric acid for 15 minutes. 68 cc. of the acid solution was removed from the paper 'by squeezing, leaving approximately 5 gm. of H 50 as a 20% solution absorbed on the paper. The prepared paper was spread out in glass dishes and heated in an oven to a top temperature of 270 F. over a 3-hour period. The black brittle product was thoroughly washed with water and dried to yield 10.1 gm. of product, a 65% yield.

9 gm. of such char or resin, 9 gm. NaOH and 29 cc. of water were charged into a high pressure bomb, which was then heated in an oil bath at 470 F. to 480 F. for four hours. The resulting thick black solution was diluted to a liter with water, filtered, then acidified with hydrochloric acid. The insoluble acids were filtered, thoroughly washed with water and dried. 8 gm. of acid product was recovered which is a 90% conversion of the char to acids, and a 50% over-all conversion of the paper to acids.

Example 9.20 gm. of predried excelsior .(white pine) was soaked for 1 hour in 200 cc. of solution containing 40 gm. of H 80 The excelsior was withdrawn holding 36 cc. of the acid solution or 7.2 gm. as H 89 absorbed in the 20 gm. of wood. The material was heated for 16 hours at 200 F. The Weight of recovered char, washed and dried as usual, was 11.1 gm. or 55.6% based on the weight of the wood.

5 gm. of the above, 2.5 gm. NaOH, and 40 cc. water were heated in a bomb at 450 F. to 480 F. for one hour. 7.5 gm. of soluble black sodium salts were recovered by drying the filtered solution formed. The pH of the solution was 11.2.

Example 10.5 gm. of starch was slurried in a. solution of 5 cc. 98% sulfuric acid in 20 cc. water. 'The paste was heated at 250 F. for 1 hour. The washed and dried char weighed 2.9 gm. for a 58% yield. Complete solubility resulted when the char plus 1.7 gm. NaOH 6 andlO cc. H O were 'heated'for 1 hour "at'480rF. t6 500 F.

Oats Company) was wetted with a solution of' 40 gm.

-H SO in 60 cc. of water; thorough mixing appeared to give uniformwettin'gj The wet material'was heated at 200 F. t0"210 'F. overnight. The black *cake'. was ground, washed, and dried'to yield 34.7-gm.-char-for a 69.4% yield.

'Example 12.20 gm. of 86.8% :pectinfwas slurried in a solution of 20 gm. H (80%) in 20 'cc. of water, and the slurry heated 1=6'hours"ats180- to 200 9 gm. of the resultant washed -andidried char .was' recovered, or a 52% yield.

5 gm. of such char +3 gm. NaOH {-'75-cc.. water were heated in the bomb atabout 480 .for 1 hour. Traces of insolubles *were'removed by;-filtration,j=and a quantitative yield of sodium: salts ofpH? 9..3.;-wasl.recovered on drying. e

Example 13.-Practically identical results to Example 12 were obtained with algin (.Keltex Corpfs' 'Kelgum) and with gum arabic.

Example 14.A sheet'of pure alpha; cellulose (52.1 gm.) was soaked in 50% by weight sulfuric aci'dythe cellulose was then squeezed-through a ringer until the total weight of cellulose vplus absorbed acid was 114.2 gms. leaving a ratio of 0.6 part H SO .-to 1 ,part of cellulose. The material was then heated;forjj19 hours at a top temperature of 182 F. The resultant black cake was ground, thoroughly washed with water, and dried to constant weight of 287 gm. "for a 55% yield.

10 gm. of this char wasconverted-to,7'.8i-gm. of acids by the bomb procedure, the aeidsisolated, washed excessively, dried and sent to the American C-yanamid Co. Stamford Research Laboratories for analyses. Results of infra-red and elementanalyses'indicatedthe products ito be high-molecular-weight polycarboxylic acids containing hydroxyl groups of indicated basic structure 12 11 3)x- Step lI W ashing char. 7

Step IlIConversi0n to alkali metal salts This step involves conversion of the char or resin into alkali metal salts of high molecular weight organic acids. This step appears in some of the examples 'aboveas a final step following the charring. Such examples are Examples 2, 7, 8, 9, 10 and 12. Additional examples are given below.

The particular resin-char used in the following: examples was prepared from paper as follows 2 31.2 gm. of paper was soaked for a half hour in a solution of gm. of 80% sulfuric acid diluted to 200 cc. volume with-water. cc. of the acid solution was separated from thepaper by decantation and squeezing, and the treated paper heated over night at F. to F. The dry char was crushed, thoroughly washed with water and dried to constant weight. The yields for two batches were 18.4 gm. and 18.5 gm. or 59% in each case. A third batch gave a yield of 60.2% of char.

A. PREPARATION OF SODIUM SALTS BY FUSION Example 15.-6 gm. of dry char and 6 gm. NaOH (C.P.) were ground together, charged into a small pressuresbomb, and heated at 480 F. to 500 F. for 1 hour. The fused mass was dried to a constant weight 11.5 gm. The resultant brownish black salts were very soluble in water.

Example 16.6 gm. of char and 4.8 gm. NaOH 'f treated as above yielded 10.4 gm. of soluble sodium salts.

Example 17.-6 gm. of char+3.6 gm. NaOH+2 gm.

salts.

B. PREPARATION OF ALKALI METAL SALTS BY DIGES- TION IN SOLUTION F ALKALI METAL HYDROXIDE Example ]8.9.3 gm. of above char, 5.6 gm. NaOH, and 150 gm. of water were charged to a bomb and heated at 460 F. to 480 F. for 1 hour. The dark black solution having pH 11.5, was filtered, and dried at 200 F. to 220 F. to yield 14.8 gm. of soluble sodium salts.

Example 19.-5 gm. of char, 4.2 gm. KOH, and 75 cc. of water were heated as usual to 480 F. for 1 hour. The yield of dry soluble potassium salts was 8.7 grams.

Example 20.-5 gm. of char, 2.165 gm. NaOH, and 30 cc. of water were heated for 5 minutes at 495 F. to 508 F. The jelly-like solution of sodium salts had a pH of 11.0.

Example 21.-The same charge as in Example 20 yielded a thick solution of sodium salts of pH 10.0 when heated for 1 hour at 480 F. to 500 F.

Example 22.A charge of 5 gm. char and 2.0 gm. NaOH (40% based on the weight of the char), and 30 cc. water were heated 15 minutes at 480 F. to 500 F. A thick solution resulted which had pH 10.3.

Example 23.--Char was prepared from Quaker Oats Companys Furafil C by mixing 30 gm. of Furafil C with a solution of 15 gm. of 98% sulfuric acid and 15 cc. of water until uniform wetting was obtained. The wet product was then heated over night at 170 F. to 180 F. The ground, washed, and dried product weighed 19.5 gm. for a 66% recovery.

5 gm. of such char, 1.5 gm. NaOH, and 25 cc. of water were heated in a bomb for 15 minutes at 500 15 F. 6 gm. of water-soluble sodium salts was obtained on drying the thick solution (pH=10.4)

Example 24.--Char was prepared from redwood sawdust exactly as described in Example 23 above for Furafil C giving a yield of 60.0% char. Only a trace of insolubles remained on heating 5 gm. of the char, 2 gm. NaOH and 25 cc. of water for only 5 minutes at 490 F. to 500 F. Water-soluble salts were recovered amounting to 6.6 gm.

Example 25.--Char resin was prepared from xylose exactly as previously described for sugar (sucrose) (Example 3). Only a trace of insolubles remained on heating 8.6 gm. of the char with 3.8 gm. of LiOH-H O in 40 cc. of water at 490 F. to 500 F. for /2 hour.

Step IV-Free acid production As has been indicated above, the free high-molecular organic acids may be produced from a water solution of the above-described alkali metal salts by acidifying the solution with a mineral acid, such as hydrochloric acid, sulfuric acid or nitric acid to any pH below about 7. This results in precipitating the desired organic acids. Such precipitate is readily separated, washed and dried.

As specific examples of the production of the free organic acids of this invention the following examples are given:

Example 26.The water solution of the alkali metal salts of Example 25 was filtered and acidized with bydrochloric acid to pH 6.5 to yield a precipitate. This precipitate when separated, washed and dried amounted to 7.4 gm. recovery from the original 8.6 gm. of char.

Example 27.-As indicated under Example 14, 10 gm. of char from pure alpha cellulose was converted to 7.8 gm. of acids by first fusing with sodium hydroxide, then dissolving in water and precipitating the acids by acidifying With sulfuric acid, the precipitated acids being separated, washed and dried to yield the mentioned 7.8 gm. of free acid product.

Example 28.-As indicated in Example 8, 9 gm. of the described paper char was converted to the sodium salts of the acids in water solution at high temperatures around 470 F. to 480 F., the solution being then acidified with hydrochloric acid. The pH of the solution was about 3. The precipitated acids were separated, washed and dried to yield 8 gm. of acid product which was a 90% conversion of the char to free acids, or a over-all conversion of the paper starting material.

CHARACTERISTICS OF CHAR RESINS AND THE ACIDS DERIVED THEREFROM In general resume, char resins were prepared from a considerable variety of raw carbohydrate materials by the two general methods outlined for the several items below:

(1) Excelsior-soaked in excess dilute H 50 with heat at 160 F. to 180 F. for 16 hours.

(2) Sucrosw-dissolved in excess concentrated H SO with exothermic heating from about 180 F. to 280 F.

(3) Redwood sawdustsame as Item 1 above.

(4) Gum arabic-same as Item 2 above.

(5) Sodium alignate--same as Item 1 above.

(6) Pectinsame as Item 1 above.

(7) Starch-same as Item 2 above.

( 8) Furafil C-same as Item 1 above.

(9) Xylosesame as Item 2 above.

The washed and dried chars of the nine items above were all converted to their free acids, with to yields, by heating 5 gm. of each char with 2.5 gm. NaOH (equivalent amount of LiOH'H O for Item 9) in 20 cc. of water at 490 F. to 510 F. for 15 minutes. Each solution of the alkali metal salts was recovered by filtering, diluting to about 1 liter, and acidifying with hydrochloric acid which precipitated the free organic acids. These high molecular weight free organic acids were in turn filtered off, washed and dried.

The similarity of the char resins and their free acids, regardless of source and method of preparation, is indicated by the activities of the acids in contaminated drilling muds, as indicated hereinafter, and also by their solubility in various solvents. Qualitative solubility tests in boiling solvents are indicated in the following table, wherein:

I =insoluble, indicated by no color in the solvents;

SS=very slightly soluble, indicated by extremely slight color probably due to soluble impurities;

S=soluble as indicated by suificient reddish black color showing the acids themselves to be somewhat soluble;

VS=very soluble.

SOLUBILITIES OF OHARS Chars Acetone Triethanolamine Benzine Benzene Xylene. Ethylene glycoL Water+ NaOH I I I I I I I I I I I I SS I I I I SS I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I l I I I I SS SS I SS I SS I SOLUBILITIES OF FREE ACIDS FROM ABOVE CHARS Dioxane SS SS SS SS SS 1 SS SS- Aceton0 I I SS I I I I Ethanol I I I I I I I Benzine I I I I I I I Ethyl acet I I SS I I I I Benzene... I I I I I I I g Xylene I I I I I I I Benzaldehyde... S S S S S S S gtlrllylcne glycol. VS VS VS VS VS VS VS t y ene g yco Monoethyl Ethel, }vs vs vs vs vs vs vs Glycerine VS VS VS VS VS VS 'Iriethanolammc VS VS VS VS VS VS Aniline SS SS SS SS SS SS Water-i-NaOlI VS VS VS VS VS VS Water+NII OH VS VS VS VS VS VS Water+tricthanolamir1e VS VS VS VS VS VS Water+Ba(OII) I I I I I Water+Ca(OH) I I I I I I I SS I I I SS- I S S VS VS VS VS VS VS VS VS SS SS VS VS VS VS VS VS I I DRILLING MUD TREATMENT The use of high molecular weight'carb'oxylic acids' and their sodium salts, of this invention, for treating drilling muds will be understood by those skilled in the art from the results supplied by the following examples. Such high-molecular-weight products are shown to be effective in various types of clay-water-base and oil-in-wateremulsion muds as commonly used by theoil industry. For laboratory purposes three basic types of muds are generally employed for testing purposes: These are:

(1) Low pH (7.5 to 10) sodium mud made up of a good sodium bentonite clay such as the commercial clay- P-95 as designated in the following tables, hydrated in relatively soft water (up to 400 g.-p.g. hardness as CaCO;,);

(2) Low pH (7.5 to 10) gypsum-contaminated salt contaminated muds made up by adding sodium clays or:- gel to extremely hard salt-contaminated watet to yield ahighly contaminated mud, or hydrating a naturally contaminated clay such as the very well 'known clay mined at Ventura, California, and designated as Dent mud in the following tables;

(3) High pH (10 to -13) lime' mud-preparedby adding lime and caustic to any clay-base drillingmud along with powdered 'lignite, Quebracho, or other.tannin,"-or*other similar well known reagent in amount sufficient to-re: tain suitable viscosity, gel"'characteristics; and water-'losscontrol properties despite' the excessivelime contamination.

Oil may be added to anyfiof the above--mudsto.formfl oil-in-water-emulsion muds. In order to show the valuable characteristics of the: present high-molecular-weight reagents in both salt and free acid form, comparative tests with .well known standard reagents which were run sir'nultaneously;'are""pri.=,

sented. Such reagents have been indicated in the following tables as:

(1) Aeropan which is a sodiumpolyac'rylate' m-arketed by American Cyan'arnid-CQ, and is a very active non-emulsifying water-loss control reagent in general-usein low pH muds, at least in California;

(2) Quebracho which is awell known tannin extract in general use for viscosity and Water-loss control in all types of clay basemuds, being'also a non-emulsifier.

All tests were run by adding the indicated number of i grams of reagent to 350 cc. of the prepared mud, these amounts being the equivalent to the same number of pounds per 42-gallon barrel of mud; Such modified mud in each test was then heated-with agitation :ina closed vvessel at F. to F. for 18' to 24 hours.

dium, and thin.

Two series of tests are furnished, the first'being with the alkali metal salts of such. acids,and the second being with the free acids themselves. The free acids are designated as X in the tables and their sodium and po- .tassium salts are designated respectively as NaX and Use of salts in mud SERIES NO. 1

(Tests on Dent clay hydrated in soft water using 350 cc. mud of 77 lbs. per cu. ft.)

cc. Water Loss Test N0. Gm. Reagent Char Source Viscosity pH 7.5 min. 15 min.

1 Blank- 30.0 Thick 6.7 2 NaX: Gum arabic 6.2 8. 4 Medium 7. 7 4 RX Paper 10.0 15.0 Thin 7.3 NaX- Pectin 6. 4 8. 6 Medium. 8.3

SERIES NO. 2

(Same mud as Series N o. 1)

{ 34 Aeropan NaX (pH 11.0) NaX (pH 10.0)

Commer i l 9.0 13 0 Thin 8 0 Sodium tetra phosphatem Commercla1; 7

Paper 6.6 9.4 Med1um.- 8 3 do a 1 7.4 10.5 .....d0 8 2 The water loss was run on-the hotmud by the standard-ARI.- 100 lbs. per sq. in. method and the water loss recorded as cc. of filtrate in 7.5 minutes'and 15 minutes. The viscosities for present purposes are recorded as thick, rue-- SERIES NO. 3

(Same mud as Series No. 1)

{Quebracho Oommercial.

8 13.4 Thin 9.4

4 9 6 Medium. 9 1 8 9 Thin 9 2 1 9 3 -do 9 4 In Series No. 3 the pH of the mud was adjusted by adding varying amounts of NaOH solution, attempting to adjust to 9.0 pH in all cases SERIES NO. 4

(Mud used was 78 lbs. per cu. it. 1 -95 clay hydrated in soft water, employing 350 cc. per test) Aeropan Commercial If Sodium tetra phosphate Commercinl NaX Furafil C 4 do 6 .do. 4 Paper 0 7.4 Medium 8.1

6 10.4 d0 8 9 8 6.2 do 9 3 6 4 8 do 9 6 8 2 do 9 4 SERIES NO. 5

(Tests on high pH lime mud of 80 lbs. per cu. ft. from Dent clay. The indicated reagents were added to the mud and the samples heated as usual for four hours.

Then 3 gm. of lime and 1 gm.

NaOH were added to each, and the heating and agitation continued for sixteen hours when the results below were obtained) Quebracho Commercial.

Blank-too thick to pour l5. 5 Thin 13+ Especially from Series No. 4 above, it will be noted that the greater the proportion of the given alkali metal salt employed, the lower is the water loss. This is particularly true in a range of about A lb. per barrel to 6 lbs. per barrel of salt in the mud and continues up to about lbs. per barrel in normal muds. As is well known to those trained in the art, the concentration of reagent required to produce a desired efiect will vary extremely with the type of mud and the particular efiect desired. As much as lbs. of a reagent per barrel of mud might prove advantageous to emulsify 20%, or 40% of oil in the mud, to overcome the effects of extreme salt or gypsum contamination, or in preparing lime muds of extreme lime concentration. Therefore, the effectiveness of a reagent can be proved, but an upper limit of practical concentration cannot be limited to the efiect on any one mud.

Use of free acids in drilling muds The free acids of this invention, as has previously such materials are predissolved in sodium hydroxide solution in the ratio required to obtain the desired pH control of the mud. The acids of the present invention similarly may be used in either way. If predissolved in caustic solution they show activities similar to those of the original sodium salts from which they were prepared. In either case, since the pH of the mud generally is above 7.5, the organic acid is present in the mud in salt form, and the activity of the acid is then effectually a measure of the activity of the soluble salts formed in the mud.

The activity of these free acids, as compared with Quebracho and lignite, is indicated in the following Series No. 6 wherein a mud of 85 lbs. per cu. ft. was prepared from the previously described P-95 clay hydrated in extremely hard water and pretreated with 1 lb. per barrel of Quebracho extract with 1 lb. per barrel (42 gals.) of sodium hydroxide (dry). From this mud various samples were prepared, heated and tested to give the results below, X representing the free acid of this invention.

SERIES NO. 6

cc. Water Loss Reagent Char Source Viscosity 7.5 min. 15 min.

NMNNNN MMNMM Blank Quebracho Lignite X been indicated, are also usable for control of viscosity in the muds and of water loss from the muds. They also have excellent oil-emulsifying characteristics.

In field practice, other organic acid materials such as tannins and powdered lignites are sometimes directly added to the drilling muds.

However, more generally trates and wall cakes which were redispersed in each instance; by volume of 32 gravityVentura crude-oil was then added to each sample; the samples were-re heated with agitation at 160 F. to 170 F. for 'four hours; and such samples again tested for water-lossand' From the table immediately above' it istapparent that the free acids and the alkali salts of this improvement possess great oil-emulsifying capacity, which improves the water-retention characteristics. Although? these tests indicate oil emulsification up to 10% oil these: acids have 40% of the mud by volume.

With reference to the charring of carbohydrates according to the present invention, the term charring and the corresponding term char signify the production of a black char resin by the respective strong mineral acid employed, the treatment, however,-not being carriedto yield a largely free-carbou-productbut'to yield a resinous reaction product, or dehydration product; which product is retractable with-strongalka li metal hydroxides such as sodium hydroxide at high temperatures to yield the described corresponding alkali metal salts which are soluble in water and from which solution the described high-molecular-weight organic acids are precipitated upon acidification.

It is apparent from the foregoing specification that the indicated char resins are producible from carbohydrates by reaction with sulfuric acid under varying conditions of temperature and ratio of acid to carbohydrate within a range of about 150 F. and about 350 F. and ratios of about 0.3 part of acid to one part carbohydrate up to a large excess of acid. Whereas resin char is formed almost instantly on reacting carbohydrate with 80% or stronger sulfuric acid at about 180 F. or above, practical application in bulk preparation allows wide apparent variations of conditions. Where the temperature of reaction is in the lower range (about 150 F. to 180 F.) and the ratio of sulfuric acid to carbohydrate is about 0.3 to l to 0.6 to 1, the time of reaction may be continued for many hours, such as 16 to 24 hours, without materially lowering the yield of desired product. However, as the ratio of acid to carbohydrate is increased and/ or the temperature is increased up to about 350 F., the time periods of heating are desirably correspondingly decreased, since otherwise the resin desired is slowly converted to carbonaceous materials which are not soluble in caustic solutions at 500 F.

The use of dilute sulfuric acid is very advantageous, particularly when the raw materials are insoluble or only slowly soluble in acid or water, since it allows uniform distribution of acid throughout the carbohydrate. Under these conditions evaporation of water to yield about 80% or higher acid concentration and subsequent charn'ng of the carbohydrate takes place smoothly without uncontrollable exothermic reaction. The speed of the conversion can be regulated both by the actual temperature of reaction and by the rate of removal of water vapor from the zone of reaction.

Such procedures thus produce the required char resins which are reactable with the alkali metal hydroxides at .25 also been capable of emulsifying oil up toxabout '.to

the-.indicatedhigh' 'temperatures=(450 to 600 F1 to" yield the indicated i water-soluble alkali imetal salts from whichthe free high+molecular-weightuwater-insoluble ore: ganic acids may he :obtairiecl .by precipitation from 'water solution upon:acidification .Inreacting'the charzwith'ithe alkali, the ratioitof alkali metal' hydroxide to char ranges betweenabout 0.3:1 andxabout 1.751 on a dry weight basis.

I claim as my inventiom' 1. A well drilling fluid comprising: rwater,';clayey sol ids; and a viscosity controlling. quantity of an: alkali metal saltof a' polycarboxylic acid produced by" reacting a carbohydrate material with an acidselected: from :the group. consisting of hydrochloric acid, :sulfur trioxide,:and sulfuric acid attemperatures limited between about F. and about 350 F:, and=.reacting the resultant .resins; with an alkali metal? hydroxide at temperatures :ibetween: aboutr450 F; and'.'600 F. to. yield the desired twater r' soluble alkali metalsaltiofapolycarboxylictacid, the ratioi of the acid to. theacarbohydratematerialon a dry basis. being'in'a .range of: about 20.3 :1 and'about. :1.5:1,' and the ratio of alkali metal 'hydroxideftothe iresins -on a dry basis being in a range? of. about 0.3 :1 to about 1.7i 1..

2.LA well drilling'ifluid comprising: water; clayey solids;iandi=an alkaliJmefaltsalt of a polycarboxylic.acidtproe duced-by reacting-fa carbohydrate material-with an acid; selected from the group consisting of hydrochloric acid, sulfurftrioxide, andsulfuric acid at 'temperature'sLbetWeen about 150 F. and aboutLTBSO IF, and reacting the re sultant resins :with an: alkali metal hydroxide :atitempera'-. tures between about450 Ffandrabout 600"F. to yield the desired water-solublemetalisalt. ofa polycarboxylic. acid, the ratio of the acid to'thericarbohydrate materialon a-dry basis-being.in 'arangeof about 03:1 and about 1.5 1, and the ratio :of alkali metal hydroxide .tothe resins on a dry basis being in a range of about 0.3:1 to about 1.7:1, the alkali metal salt being in the range of about pound to about 20 pounds per 42 gallon barrel of the fluid.

3. An oil-in-water emulsion comprising: water; petroleum oil; and an alkali metal salt of a polycarboxylic acid produced by reacting a carbohydrate material with an acid selected from the group consisting of hydrochloric acid, sulfur trioxide, and sulfuric acid at temperatures between about 150 F. and about 350 F., and reacting the resultant resins with an alkali metal hydroxide at temperatures between about 450 F. and about 600 F. to yield the desired water-soluble metal salt of a polycarboxylic acid, the ratio of the acid to the carbohydrate material on a dry basis being in a range of about 0.321 and about 1.5 1, and the ratio of alkali metal hydroxide to the resins on a dry basis being ina range of about 0.321 to about 1.7:1, the alkali metal salt being in the range of about A pound to about 20 pounds per 42 gallon barrel of the emulsion.

4. A well drilling mud comprising: water; clayey solids; and from about lb. to about 20 lbs. per 42-gallon barrel of a reaction product obtained by reacting a carbohydrate material containing at least 5 carbon atoms per sugar unit of a molecule with sulfuric acid at about 150 F. to about 350 F. to produce a resin, and digesting the resin with an alkali metal hydroxide at temperatures between about 450 F. and about 600 F. to produce water-soluble alkali metal salts of high-molecular-weight polycarboxylic acids which are produced by reaction of the resin with the alkali metal hydroxide, the ratio of the sulfuric acid to the carbohydrate material on a dry basis being in the range of about 0.3:1 to about 1.5:1, and the ratio of alkali metal hydroxide to the resins on a dry basis being in the range of about 0.3:1 to about 1.7:1.

5. A well drilling fluid comprising: water; clayey solids; and a viscosity controlling quantity of a polycarboxylic acid produced by reacting a carbohydrate material with an acid selected from the group consisting of hydrochloric acid, sulfur trioxide, and sulfuric acid at temperatures limited between about 150 F. and about 350 F., reacting the resultant resins with an alkali metal hydroxide at temperatures between about 450 F. and 600 F. to yield a water-soluble alkali metal salt of a polycarboxylic acid, and acidifying the alkali metal salt to form the desired corresponding polycarboxylic acid, the ratio of the acid to the carbohydrate material on a dry basis being in a range of about 03:1 and about 1.5 1, and the ratio of alkali metal hydroxide to the resins on a dry basis being in a range of about 0.3:1 to about 1.721.

6. A well drilling fluid comprising: water; clayey solids; and a polycarboxylic acid produced by reacting a carbohydrate material with an acid selected from the group consisting of hydrochloric acid, sulfur trioxide, and sulfuric acid at temperatures between about 150 F. and about 350 F., reacting the resultant resins with an alkali metal hydroxide at temperatures between about 450 F. and about 600 F. to yield a water-soluble alkali metal salt of a polycarboxylic acid, and acidifying the alkali metal salt to form the desired corresponding polycarboxylic acid, the ratio of the acid to the carbohydrate material on a dry basis being ina range of about 0.3:1 and about 1.5 :1, and the ratio of alkali metal hydroxide to the resins on a dry basis being in a range of about 0.321 to about 1.7: 1, the polycarboxylic acid being in the range of about pound to about pounds per 42 gallon barrel of the fluid.

7. An oil-in-water emulsion comprising: petroleum oil; water; and a polycarboxylic acid produced by reacting a carbohydrate material with an acid selected from the group consisting of hydrochloric acid, sulfur trioxide, and sulfuric acid at temperatures between about 150 F. and about 350 F., reacting the resultant resins with an alkali metal hydroxide at temperatures between about 450 F. and about 600 F. to yield a water-soluble alkali metal salt of a polycarboxylic acid, and acidifying the alkali metal salt to form the desired corresponding polycarboxylic acid, the ratio of the acid to the carbohydrate material on a dry basis being in a range of about 03:1 and about 15:1, and the ratio of alkali metal hydroxide to the resins on a dry basis being in a range of about 0.311 to about 1.7:1, the polycarboxylic acid being in the range of about pound to about 2.0 pounds per 42 gallon barrel of the emulsion.

8. A well drilling fluid comprising: water; clayey solids; and from about 4 lb. to about 20 lbs. per 42-gallon barrel of a reaction product obtained by reacting a carbohydrate material containing at least 5 carbon atoms per sugar unit of a molecule with sulfuric acid at about F. to about 350 F. to produce a resin, digesting the resin with an alkali metal hydroxide at temperatures between about 450" F. and about 600 F. to produce watersoluble alkali metal salts of high-molecular-weight polycarboxylic acids which are produced by reaction of the resin with the alkali metal hydroxide, the ratio of the sulfuric acid to the carbohydrate material on a dry basis being in the range of about 0.3: 1 to about 1.5 1, and the ratio of alkali metal hydroxide to the resins on a dry basis being in the range of about 0.3:1 to about 1.7 :1, and acidifying the resulting material to form the desired reaction product.

References Cited in the file of this patent UNITED STATES PATENTS 2,604,447 Cummer et al July 22, 1952 2,713,030 Brink et al July 12, 1955 2,785,125 Salathiel Mar. 12, 1957 2,881,211 Sperry Apr. 7, 1959 FL... Hume" 

1. A WELL DRILLING FLUID COMPRISING: WATER, CLAYEY SOLIDS, AND A VISCOSITY CONTROLLING QUANTITY OF AN ALKALI METAL SALT OF A POLYCARBOXYLIC ACID PRODUCED BY REACTING A CARBOHYDRATE MATERIAL WITH AN ACID SELECTED FROM THE GROUP CONSISTING OF HYDROCHLORIC ACID, SULFUR TRIOXIDE, AND SULFURIC ACID AT TEMPERATURES LIMITED BETWEEN ABOUT 150* F. AND ABOUT 350*F., AND REACTING THE RESULTANT RESINS WITH AN ALKALI METAL HYDROXIDE AT TEMPERATURES BETWEEN ABOUT 450*F. AND 600*F. TO YIELD THE DESIRED WATERSOLUBLE ALKALI METAL SALT OF A POLYCARBOXYLIC ACID, THE RATIO OF THE ACID TO THE CARBOHYDRATE MATERIAL ON A DRY BASIS BEING IN A RANGE OF ABOUT 0.3:1 AND ABOUT 1.5:1, AND THE RATIO OF ALKALI METAL HYDROXIDE TO THE RESINS ON A DRY BASIS BEING IN A RANGE OF ABOUT 0.3:1 TO ABOUT 1.7:1. 